Hi Woodman long time no see!!
You could have let her come home. It would not have stopped anything. She still would have sunk into the rabbit hole. The outcome would have been the same it just may have taken longer with more casualties of war. You may have lost your sanity along the way, and your kids would have watched this front and center which could have had much more detrimental effects on them than the way you decided to handle it. You protected them as you should have. Had you not had children your approach may have been something else. I applaud you for making a really difficult decision and protecting your children a lot of people don't. Its just not worth sacrificing a child to accommodate the desires of an alcoholic even if those desires tug at the heart strings. It sucks to do what is right when appeasement can be the (seemingly) easier choice.
I wish we could apply logic to emotion. Time is what it takes - you obviously loved her very much that was always evident in your postings. I agree that grief counseling would do you a world of good.